High speed rotary hydraulic motor



Nov. 7, 1967 E. 1.. ACKLEY 3,350,935

HIGH SPEED ROTARY HYDRAULIC MOTOR Filed Feb. 26, 1965 Edward LacklINVENTOR.

3 BY 'y United States Patent ()fl" 3,350,985 Patented Nov. 7, 19673,350,985 HIGH SPEED ROTARY HYDRAULIC MOTOR Edward L. Ackley, 1916 SE.50th, Portland, Greg. 97215 Filed Feb. 26, 1965, Ser. No. 435,471 2Claims. (Cl. Ell-87) ABSTRACT OF THE DISCLOSURE A cylindrical casehouses recessed front, rear and central core segments supporting a driveshaft. One of a pair of gears in the central segment is secured to thedrive shaft, and hydraulic fluid under pressure is conveyed to and fromthe gears through passageways in the front seg ment and conduits in ahandle connected to the case. Bearings and seals are associated with thesegments and drive shaft, and the outer end of the latter supports arotary tool.

This invention relates to high speed rotary hydraulic motors.

Although various types of rotary hydraulic motors are we1l-known, needexists for an improved motor of this classwhich may be appliedsatisfactorily to heavy duty uses such as the operation of high speedrotary pruning saws.

.It accordingly is the general purpose of the present invention toprovide a heavy duty, high speed, hydraulic motor:

( 1) which operates at exceptionally high speed, for example, at speedsof in exces of 15,000 r.p.m.;

(2) which does not heat excessively, even when operated In the drawings:

FIG. 1 is a longitudinal sectional view of the rotary hydraulic motor ofmy invention;

FIGS. 2 .and 3 are front and back elevations of the motor, respectively,FIG. 2 being partly in section;

FIG. 4 is a fragmentary, detail sectional view taken along line 4-4 ofFIG. 3 and illustrating the manner of assembling the motor;

FIG. 5 is a fragmentary, sectional view taken along line 55 of FIG. 1and illustrating a novel gear drive which may be employed in the motor;and

FIG. 6 is an enlarged fragmentary view illustrating seal means employedin the motors of my invention to seal the motor against leakage of highpressure hydraulic fluid.

The motor of my invention is illustrated in the drawings in itsapplication to a rotary pruning saw although it is applicable also toInanyother uses. As shown particularly in FIGS. 1, 2, and 3, the saw.ishoused in a case 10 comprising a short, hollow cylinder open on bothends and made of stout metal.

The case is provided with a connector 12 comprising a short pipe whichextends at right angles to the case communicating with the interiorthereof. It telescopes over a hollow handle 14 which in a pruning sawapplication may be twelve or fifteen feet long.

The handle, in turn, houses hydraulic fluid conduits 16, 18, the onebeing for the transmission of input fluid under pressure and the otherfor the transmission of exhaust fluid. These may be included in anhydraulic circuit designed to provide hydraulic fluid under pressure tothe motor as required for its operation.

Case 10 houses a transversely segmental core which in the illustratedform of the invention includes three longitudinally recessed segments: arear segment 20, a central segment 22, and a front segment 24.

Front segment 24 is formed with first connecting passageways 26, 28 andsecond connecting passageways 30,.

32 which communicate, respectively, with input and exhaust conduits 16,18 by means of which hydraulic fluid is supplied to and exhausted fromthe driving elements of the motor.

A seal ring 34 and a seal ring 36 are associated, respectively, withpassageways 26 and 30 to prevent the escape of fluid.

Securing means are provided for securing the core segments to each otherand for securing the assembled core.

in the case. It is a particular feature of the invention that thesecuring means used permit easy disassembly and assembly of the motor asrequired for its servicing and repair.

To achieve this purpose, there are provided a plurality.

of cap screws 40 which penetrate segments 20 and 22 and which arethreaded into front segment 24, being arranged 44 which are insertablein registering apertures in thesegments when the segments are arrangedin proper relation for coupling them by. means of screws 40, 42.

The recess in central core segment 22 provides a chamber 48, FIG. 5.Thischamber is sealed off by means of seal rings 50, 52.

Meshing hydraulic gears 54, 56 work in chamber 48. As will be noted fromFIG. 5, the teeth of these gears are unique in that they extend radiallyfrom the gear base and are tapered uniformly toward an outer terminalapex.

At no place in their contour are the gear teeth undercut.

As result, they mesh smoothly without trapping oil during any phase oftheir operation. This in turn assists in keeping the heat generated byoperation of the motor at a minimum. It also assists in reducing theoperating vibration.

Hydraulic gear 54 is keyed to a shaft 58, the ends of which arejournaled in needle bearings 59.

Hydraulic gear 56 is keyed or otherwise fixed to the drive shaft of themotor, indicated generally at 60. Shaft 60 is free to movelongitudinally within limits thereby avoiding applying a thrust forceagainst the gear, with consequent development of heat.

Shaft 60 is elongated, extending completely through case in an axialdirection. It is stepped in its longitudinal configuration beingprovided with an inner section 62 of relatively restricted diameter andan outer section 64 of relatively substantially enlarged diameter, thetwo sections being separated by an annular shoulder 66.

Inner section 62 of shaft 60 mounts gear 56. It is journaled in suitablebearings such as needle bearings 68 positioned one on each side of thegear.

As is apparent in FIG. 1, the outer end of outer enlarged section 64 ofdrive shaft 60 extends completely beyond the plane of case 10 and mountsthe appliance to be driven by the motor. Thus the outer end of the shaftmay be threaded and may mount a saw blade 70 between clamps 72. Nut 74threaded on the end of the shaft supplies the clamping pressure requiredreleasably to mount the saw blade.

It is a particular feature of the invention that shaft 64) is supportedin bearing means which braces the shaft against thrust in bothdirections, as Well as against radial stresses, thereby relievingwearing strain which otherwise would be exerted on the motor gears andalso reducing the tendency of the motor to develop heat at highoperating speeds. To this end there is provided a husky bearing 80 whichmay comprise an assembly of one or more ball or roller bearings arrangedend to end with the inner end of the bearing abutting against shoulder66 of the shaft.

Retaining means are provided for retaining bearing 80 in place while atthe same time resisting shaft thrust in both directions.

The retaining means include a first snap ring 82 seated in the recess infront core segment 24 and bearing against the outer margin of bearing80. This ring takes the thrust of the drive shaft when the thrust isexerted outwardly, or to the right as viewed in FIG. 1.

Seated on the outer end of enlarged section 64 of shaft 60 is a secondretaining ring 84. This also is adjacent the outer end of bearing 80. Ittakes the thrust of the drive shaft when the thrust is exerted inwardly,i.e. toward the left as viewed in FIG. 1.

It thus will be noted that bearing 80, which journals the enlargedsection of the drive shaft, takes the major portion of the workingstresses occurring during operation of the motor, whether the stressesoccur radially or endwise. This in turn saves stress and wear on therelatively sensitive gears of the motor.

Another particular feature of the invention is the provision of novelseal means along the drive shaft for preventing the escape of highpressure hydraulic fluid from the gear chamber. The construction of theseal means is shown in FIGS. 1 and 6.

A seal retainer 90 is seated in the longitudinal recess in core segment24, being. arranged coaxially with the inner restricted section 62 ofthe drive shaft 60. It is located inside of shoulder 66 and is retainedin place by means of a snap ring 92 seated in core segment 24. The outerperipheral surface of seal retainer 90 is recessed to accommodate astatic seal O-ring 94.

Retainer 90 houses a seal member 96 which likewise is coaxial withsection 62 of shaft 60 against which it bears. Its outer peripheralsurface is recessed to accommodate a static seal O-ring 98. Its innerperipheral surface is recessed to accommodate a quad-ring 100.

The materials of which the sealing elements are composed is ofimportance in determining the efficiency and service life of the seal.It is one of the objects of my invention to fabricate shaft section 62,seal 96 and quadring 100 of relative materials having frictioncharacteristics such that the friction coefficient of quad-ring 100 withreference to shaft section 62 will be greater than the frictioncoefficient of the quad-ring with reference to seal 96.

For example, where shaft section 62 is of metal, quadring 100 of rubberand seal 96 of molybdenum sulfidelubricated nylon, the frictionalcoefiicient of the rubber quad-ring with reference to the metal shaftsection will be greater than its frictional coefficient with respect tothe lubricated nylon seal ring.

As a consequence, during high speed operation of the motor, quad-ring160 will rotate within the recess in which it is housed to an extentsufficient to relieve the stress and prevent slippage of O-ring 98, thuspreserving the static seal afforded by the latter ring. This feature notonly improves the seal but also lengthens the service life of thesealing member substantially.

It thus will be seen that the construction of the motor herein describedis such as to achieve the various objects of the invention.

The motor may be assembled and disassembled rapidly and easily simply byinserting or removing screws 40 and 32. During high speed operation ofthe motor the pointed teeth of gears 54, 56 mesh cleanly withouttrapping oil, thereby reducing friction and heat generation.

Large bearing on the enlarged portion of stepped shaft 60 takes themajor portion of the developed stress during heavy duty service,including both the radial stress and the thrust stress in bothdirections. Wear on gears 54, 56 as well as on bearings 59, 68 thus isminimized.

In addition, the efficiency of the hydraulic fluid seal is greatlyimproved first, by locating it on section 62 of the drive shaft whichhas a peripheral speed substantially less than that of enlarged section64, and secondly by providing the special inner seal arrangementillustrated in FIG. 6 above described which prevents wear of the sealingelements.

The motor accordingly is characterized by a long and efficient servicelife even when applied to the operation of high speed, heavy dutyequipment such as rotary pruning saws.

It is to be understood that the form of my invention herein shown anddescribed is to be taken as preferred example of the same and thatvarious changes in the shape, size and arrangement of parts may beresorted to without departing from the spirit of my invention or thescope of the subjoined claims.

Having thus described my invention, I claim:

1. A high speed rotary hydraulic motor comprising (a) a cylindrical caseopen at both ends,

(b) a handle mounting the case,

(0) hydraulic fluid input and exhaust conduits mounted on the handle,

(d) in the case a transversely segmental core comprising recessed front,back and central segments, the front segment having hydraulic fluidinput and exhaust passageways communicating the input and exhaustconduits with the recessed central segment,

(e) securing means securing the core segments together and securing thecore in the case,

(f) a pair of meshing hydraulic motor gears journaled in the core andarranged in the recessed central'segment to be driven by hydraulic fluidunder pressure circulating in the input and exhaust conduits andpassageways,

(g) a motor drive shaft extending in the axial direction of the case andhaving an outer end portion extending outward from the front coresegment and having tool mounting means thereon and an inner end por- 2.The motor of claim 1 wherein the teeth of the hy-. draulic motor gearsare arranged radially at spaced intervals about the periphery of thegear, each tooth beingi 5 6 uniformly tapered in a radial direction to apoint at its 2,938,438 5/1960 Hamilton 91-87 X apex. 3,076,684 2/1963Todtenhaupt 30836.3 X

References Cited UNITED STATES PATENTS FOREIGN PATENTS 1,769,030 7/1930Lassen 308-363 5 572,631 3/1933 Germany- 2,391,577 12/1945 Larson103--126 X 2,466,972 4/1949 solmer 91 87 X MARTIN P. SCHWADRON, PnmaryExammer.

2,632,424 3/1953 Solmer 91-87 X G. N. BAUM, Assistant Examiner.

1. A HIGH SPEED ROTARY HYDRAULIC MOTOR COMPRISING (A) A CYLINDRICAL CASEOPEN AT BOTH ENDS, (B) A HANDLE MOUNTING THE CASE, (C) HYDRAULIC FLUIDINPUT AND EXHAUST CONDUITS MOUNTED ON THE HANDLE, (D) IN THE CASE ATRANSVERSELY SEGMENTAL CORE COMPRISING RECESSED FRONT, BACK AND CENTRALSEGMENTS, THE FRONT SEGMENT HAVING HYDRAULIC FLUID INPUT AND EXHAUSTPASSAGEWAYS COMMUNICATING THE INPUT AND EXHAUST CONDUITS WITH THERECESSED CENTRAL SEGMENT (E) SECURING MEANS SECURING THE CORE SEGMENTSTOGETHER AND SECURING THE CORE IN THE CASE, (F) A PAIR OF MESHINGHYDRAULIC MOTOR GEARS JOURNALED IN THE CORE AND ARRANGED IN THE RECESSEDCENTRAL SEGMENT TO BE DRIVEN BY HYDRAULIC FLUID UNDER PRESSURECIRCULATING IN THE INPUT AND EXHAUST CONDUITS AND PASSAGEWAYS, (G) AMOTOR DRIVE SHAFT EXTENDING IN THE AXIAL DIRECTION OF THE CASE ANDHAVING AN OUTER END PORTION EXTENDING OUTWARD FROM THE FRONT CORESEGMENT AND HAVING TOOL MOUNTING MEANS THEREON AND AN INNER END PORTIONSECURED TO ONE OF THE GEARS,